Log of SQL statement parameters just puts "null" when not printable. Make it clearer

The SQL statement invoked is always printed in the DN log, with parameter surrounded by angle-brackets (or not if specifying the persistence property). Any parameter that is not of an immediately printable type is just shown as
<null>
yet the parameter is not actually null. Make it more distinct that a value was provided.

Description

The SQL statement invoked is always printed in the DN log, with parameter surrounded by angle-brackets (or not if specifying the persistence property). Any parameter that is not of an immediately printable type is just shown as
<null>
yet the parameter is not actually null. Make it more distinct that a value was provided.